This invention relates to a machine for configuring, by rolling, an open end of a thin metal cylinder or shell and in particular a shell from which a can, such as a beverage can, is to be completed. The term "shell" or "cylindrical shell" is used herein generically to designate either a regular one-piece cylinder (geometrically "regular") open at both ends (used to make a so-called three-piece can) or a one-piece elongated cup-shaped member open at one end and having a closed bottom wall at the opposite end from which a two-piece can may be completed by adding a lid. The configuration may be one of necking-in, flanging, or both, for example.
According to U.S. Pat. No. 4,563,887 the open end of a thin-walled cylindrical metal shell is spin-rolled to form a reduced neck and flange. This is done by rotating the shell about its longitudinal axis while engaging the outer side of the shell, at the open end, with a forming roller or die opposed to a mandrel at the inside of the open end of the shell. The forming roller and mandrel have opposed surfaces, and are mounted for relative axial movement, by which the necking and flanging operations are completed as an incident to feeding or advancing the die-forming roller toward the mandrel with the open end of the shell squeezed between them. The operative or effective position of the mandrel is achieved by mounting it eccentrically on a shaft and oscillating the shaft until the mandrel is orbited into engagement with the inside wall of the shell.
The shell is spun or rotated rapidly about its longitudinal axis by means including a rotating chuck which clamps the shell at the end opposite the open end which is to be configured. The chuck thus constitutes a tool which spins the shell, while the mandrel and opposed forming roller are the tools by which the open end of the can or shell is deformed. Collectively they represent tooling with which the present invention is for the most part concerned.